Eight British explorers begin a gruelling trek on Friday to try to solve the mystery behind the greatest disaster to befall a polar expedition.

In 1845 Sir John Franklin set off to discover the North West Passage - a much sought after trade route to link the Atlantic and Pacific oceans - in his ships, the Erebus and Terror.

But Sir John - celebrated for surviving a previous expedition by eating his own boots - and his 129 men were never to return.

The Franklin Memorial Expedition will be the first to retrace Sir John's final 200-mile (322-kilometre) trek from his landing at Victory Point on King William Island in the Arctic Ocean, to Starvation Cove, where the expedition's last traces - bones, boots and an upturned boat - were found.

The main reason for the expedition was to learn about what
Franklin did and get a better understanding of what happened to his men - there
have been so many rumours

Team leader Rebecca Harris

The team's leader and only woman, 34-year-old art director Rebecca Harris, is determined to discover what went wrong during Sir John's final
expedition.

"The main reason for the expedition was to learn about what Franklin did and get a better understanding of what happened to his men - there have been so many rumours."

The rumours range from lead poisoning to cannibalism.

But Ms Harris believes the men probably died as a result of a variety of ailments including scurvy, cold-related injuries and pure exhaustion, mainly because they had no real comprehension of what they were undertaking.

"I think they died where they fell along the way and Franklin probably died of natural causes like a heart attack.

"How we are prepared for the expedition is incomparable - we know so much more about health and nutrition now.

"It's daunting and will be very tough going - but we've got a great team."

The team have 200 miles to walk

One member of that team is Dr Mark Wilson, who has experience in treating cold-related injuries from his time working with the Himalayan Mountain Rescue Service.

Dr Wilson, 28, who works at the East Surrey Hospital in Redhill, was asked to join the team after the original doctor was called to the Gulf two months ago.

He said: "I'm excited about the trip, but nervous about the responsibility.

"There is so much you rely on as a doctor - but I'm taking most things that a GP would prescribe, like antibiotics."